1,720,975 research outputs found
New method for the early design of BIPV with electric storage: a case study in northern Italy
Get PDFThis paper presents a new method for the planning of photovoltaic systems in the early architectural design. The method finds capacity and position of a photovoltaic system over the envelope of a building by means of optimization. The input consists in: geometry of the building, surrounding shadings, local weather, hourly electric demand, unitary costs of the system and benefits for the production of electricity (sold or self-consumed). In the input there are known values (e.g. PV installation costs [€/kWp] or present costs for the electricity [€/kWh]) and unknown ones (e.g. degradation rate [%/year], maintenance costs [€/kWp year] or discount rate [%/year]). The optimization is performed using the expected value out of a set of parametric scenarios generated by the unknown input values. The results show that, if capacity and position of the system are tailored on its aggregated electric demand, a large penetration of photovoltaic electricity is profitable at current prices without incentives or valorization from the grid. The optimization performed with an arbitrary set of electric storages shows how the presence of storage fosters a higher optimal capacity for the PV system. This method has the potential to hugely expand the installation of urban photovoltaic
CO2 measurements for unconventional management of indoor air quality
No full textCarbon dioxide (CO2) is a known global pollutant and is responsible for the global warming that the planet has been experiencing for the last few decades. On a local scale, outdoor CO2 does not pose any risk for the environment and humans. Risks are usually far from involving human beings in the majority of indoor environments, although high CO2 concentrations may entail temporary adverse effects that are similar to the typical symptoms of the so-called “sick-building syndrome”. Such effects become even more important on workplaces or at school/university, since high CO2 levels may negatively influence the productivity and the learning capability of individuals. To understand the magnitude of the problem, a monitoring campaign was carried out in four classrooms and in a library of a university in northern Italy. Three of the classrooms under observation were not equipped with an air extraction system. The CO2 concentration was monitored with low-cost non-dispersive infrared digital sensors in two periods of the year: between February and March and at the end of May. During those periods, the number of occupants, temperature and relative humidity were also monitored, as well as any opening of the windows (where available). The results showed that, where automatic air extraction is not available, CO2 concentrations can exceed 5,000 ppm. In general, the lower the ratio between the room volume and the number of occupants, the higher the concentrations achieved. The installation of lowcost sensors might prove useful to prevent the negative effects from the exposure to high CO2 levels and help achieve more sustainable conditions in indoor spaces, since the sensors could inform lecturers and students on the need for opening doors and/or windows when air extraction is not provided.Carbon dioxide (CO2) is a known global pollutant and is responsible for the global warming that the planet has been experiencing for the last few decades. On a local scale, outdoor CO2 does not pose any risk for the environment and humans. Risks are usually far from involving human beings in the majority of indoor environments, although high CO2 concentrations may entail temporary adverse effects that are similar to the typical symptoms of the so-called “sick-building syndrome”. Such effects become even more important on workplaces or at school/university, since high CO2 levels may negatively influence the productivity and the learning capability of individuals. To understand the magnitude of the problem, a monitoring campaign was carried out in four classrooms and in a library of a university in northern Italy. Three of the classrooms under observation were not equipped with an air extraction system. The CO2 concentration was monitored with low-cost non-dispersive infrared digital sensors in two periods of the year: between February and March and at the end of May. During those periods, the number of occupants, temperature and relative humidity were also monitored, as well as any opening of the windows (where available). The results showed that, where automatic air extraction is not available, CO2 concentrations can exceed 5,000 ppm. In general, the lower the ratio between the room volume and the number of occupants, the higher the concentrations achieved. The installation of low-cost sensors might prove useful to prevent the negative effects from the exposure to high CO2 levels and help achieve more sustainable conditions in indoor spaces, since the sensors could inform lecturers and students on the need for opening doors and/or windows when air extraction is not provided
A Spatial Decision Support System for thermal energy planning at the regional scale
Get PDFThe focus of the Ph.D. dissertation is on the thermal part of the energy planning issue since the space conditioning (heating and cooling – H&C) of buildings represents about 75% of the energy consumed by European residential buildings and only 16% of the heating and cooling consumption is covered by renewable energy sources (RES). At the same time, the increased complexity of the spatial planning process when energy issues are involved has made clear the need for new “energy-aware” tools and methods used in this field.
The proposed methodology is GIS (Geographical Information System)-based and performed at regional scale given that the movement of energy planning activities from national to regional and local scale allows a much more detailed analysis of both the energy demand and supply, balancing them more effectively. The integration of the spatial dimension within energy analyses can also provide the decision-makers with a spatially-explicit approach towards the energy transition and the development of sustainable energy plans and strategies. The general aim of the Ph.D. thesis is to develop a Spatial Decision Support System (SDSS) allowing the decision-makers to take into account (during the planning process) both the improvement of the energy production from RES and the energy renovation of the existing building stock. The SDSS aims also to connect the energy planning (supply side) with spatial planning (demand side) by seeking synergies between the two fields. This connection is made taking advantage of the framework of the Strategic Environmental Assessment (SEA).
The Ph.D. thesis is partially developed within a European co-financed project included in the Interreg Alpine Space programme. The GRETA project was designed to foster the use of shallow geothermal energy (SGE) in energy plans and strategies along the Alps. SGE is a low-carbon source for H&C of buildings, which exploits the heat stored within the ground, a local source widely available and less dependent from changes in time compared to other RES. Despite this, its exploitation is not yet diffused and its growth is limited mainly by factors such as scarce knowledge, complicated and fragmented legislation, and high installation costs. Considering all these issues, the research questions that shaped the Ph.D. activities are:
➢ How to estimate the thermal energy demand of the residential building stock at the regional scale, as a starting point for developing sustainable energy strategies aimed at the reduction of the thermal energy consumption in the existing buildings.
➢ How to integrate this appraisal in the energy planning of a region in order to elaborate different scenarios for the energy balance between thermal demand and supply, fostering the use of shallow geothermal energy (SGE) that is a renewable source still not well-known and not exploited.
➢ How to encourage the connection between energy planning and spatial planning towards the common goal of sustainable energy transition, helping to fill the gap between the development of plans and strategies and their implementation, thanks to the Strategic Environmental Assessment (SEA) framework.
The proposed methodology has been applied in a case study, i.e. Valle d’Aosta, an Italian alpine region. Almost all the data processing is performed with open-source software (GRASS GIS, QGIS, Python, and R) and applying a spatially-explicit approach, for pushing the integration of the spatial dimension in the energy analysis. The spatial units of analysis are the single building and the census tract. The single building has been chosen as the smallest unit available for ensuring a better characterization of the thermal energy demand and of the potential energy production from SGE. Moreover, the scenario analysis for the energy renovation of buildings is better performed at the building level; so, it is particularly suitable for developing an SDSS. Nevertheless, some data processing is done at the census tract level, using aggregated and statistical information to estimate the required values at the building level. The reason for this twofold scale of analysis is that the data availability often changes depending on time, space and data provider. For instance, for the case study area only little data was available at the building level for the whole region. Therefore, the methodology integrates data from different sources to fill this knowledge gap.
The methodology applied in the case study is divided into two parts:
1) The first one concerns the data collection and processing for the spatial estimation of the space heating demand of the existing building stock. At the end of it, the technical and economic suitability of SGE (performed within the GRETA project) for covering the energy demand of buildings and replacing some fossil fuels is evaluated.
2) The second one is carried out in the framework of SEA, by defining common objectives and developing scenarios for the integration of SGE in the energy planning process, as the short-term objective, and the coordination of energy and spatial planning goals, as the long-term objective. In the Ph.D. thesis, SEA is intended as a conceptual framework for integrating energy and spatial planning, rather than as an evaluation tool.
The main outputs of the Ph.D. thesis are: (i) the spatial evaluation of the space heating demand of each residential building of the case study, without using the “archetypes approach”; (ii) the development of a method for the integration of data from different sources and for its estimation if missing at the building level; (iii) the use of SEA as a framework for connecting energy planning and spatial planning fields, to support strategic decision-making processes. Even though the Ph.D. case study is a typical alpine region, (iv) the developed methodology can be applied at different scales and not only on alpine regions but potentially in every kind of context. Since it strongly depends on the availability of data, the replicability of the methodology is quite high.
The main expected impacts of these outputs are: (1) SDSS allows to reach a trade-off between the number of input data and the level of detail often required by decision-makers; (2) SDSS can support the decision-makers allowing them to analyse from various viewpoints different energy scenarios and also to localise where is better to address the energy measures; (3) the results at the building level represent a starting point for defining and developing strategies for the energy transition of settlements at different scales; (4) SEA used as a strategic tool for integrating energy and spatial planning, by coordinating strategic objectives, and linking the thesis outputs to the energy decision-making process
Sunspaces for passive building heating: calculation models and utilization of empirical data
No full textThe thesis deals with sunspaces, considered as a particular passive solar system. Solar systems exploit solar radiation in order to decrease the use of non-renewable energy sources. Therefore their importance is both environmental and economic. According to “The passive solar energy books” (1979) of Edward Mazria the difference between “active systems” and “passive systems” is that in the latter the heat flows happen without mechanical equipment. The present research focuses on the reduction of winter energy requirements due to the presence of a sunspace, it analyses the involved physical phenomena, and it considers tools to design sunspaces and to optimize them from the point of view of energy requirements.
Particular attention is given to the quasi-steady-state methods, which are the most used by the designers. The thesis critically analyses calculation methods, identifies their problematic aspects and provides some indications to improve the method of the technical standard EN ISO 13790:2008.
As well as by the theoretical part, in the research a fundamental role is played by experimental campaigns. In fact, empirical data have been collected in relation both to existing sunspaces and to sunspaces which were specifically constructed for the research. Two sunspaces, one having the dimensions of a small room and the other one which is its scale model, with halved dimensions, were created and were the object of an experimental campaign. This experimental study has allowed to observe how the physical behaviour of sunspaces changes by changing their dimensions and to achieve a deep comprehension of sunspaces through quantitative analyses of involved physical quantities. A virtual model of the sunspaces was created and validated.
Because of the long renovation cycle for buildings, the improvement of the energy performance of existing buildings is fundamental. That is the reason why part of the research concerns the refurbishments of verandas which are closed with elements having a large glazed surface. The concept is the same as for the sunspaces: the presence of an adjacent not heated space which works as “solar collector” can decrease the heating requirements. An existing building in Freiburg (Germany), which was renovated between 1997 and 1999 (among other things, by closing the veranda with windows, improving the insulation, and adding a solar air collector for the supply air entering the veranda and a mechanical air extraction system), was monitored (in collarboration with Fraunhofer ISE) and the data were analysed critically. Considering the experience with the past renovation, design proposals for future refurbishments have been considered. The energy performances of different possibilities are calculated and compared among them. Attention is paid to thermal insulation, to exploitation of the solar radiation and to ventilation strategies (also mechanical and integrated with heat recovery systems).
A guided procedure for the proper design of sunspaces is presented. Its goal is to present clearly and with a logical sequence what aspects the designers have to take into account to design sunspaces properly. Both new constructions and refurbishments are considered. Aspects such as the relationship between building shape and heating requirements, local context, insulation, thermal inertia, overheating, ventilation, and so on are dealt with.
The technology to build a sunspace is simple, but a rigorous study of its behaviour is complex. Future researches about the thermal behaviour of sunspaces could develop further the possibility to improve the quasi-steady-state methods, taking in consideration, also from a quantitative point of view, a lot of different cases. The utilization of CFD software, in order to better estimate the convective heat coefficients and to evaluate the ventilation from a sunspace, could be another development of this subject
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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